Automobiles and light trucks usually have hydraulic service brakes and cable actuated parking brakes. Parking brakes, by law, are restricted to the use of mechanical braking force. However, since conventional parking brakes can apply one about one tenth the braking force that hydraulically actuated service brakes can apply, there are often quite ineffective at stopping a vehicle during an emergency, such as when the service brakes fail while the vehicle is moving. The result of a service brake failure, or the failure of parking brakes such as when parked on a steep incline, is often catastrophic.